Joint Test Action Group (JTAG) is the usual name used for the
IEEE 1149.1 standard entitled Standard Test Access Port and Boundary-Scan Architecture for test access ports used for testing
printed circuit boards using
boundary scan.JTAG was an industry group formed in 1985 to develop a method to test populated circuit boards after manufacture. At the time, multi-layer boards and non-lead-frame
ICs were becoming standard and making connections between ICs not available to probes. The majority of manufacturing and field faults in circuit boards were due to
solder joints on the boards, imperfections in board connections, or the bonds and bond wires from IC pads to pin lead frames. JTAG was meant to provide a pins-out view from one IC pad to another so all these faults could be discovered. The industry standard finally became an
IEEE standard in
1990 as IEEE Std. 1149.1-1990 after many years of initial use. That same year
Intel released the first
processor with JTAG: the 80486 which led to quicker industry adoption by all manufacturers. In
1994, a supplement that contains a description of the
boundary scan description language (BSDL) was added. Since then, this standard has been adopted by
electronics companies all over the world. Boundary-scan is nowadays mostly synonymous with JTAG.
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